The present invention relates to a fault inspection system for inspecting an abnormal noise of a vehicle generator or the like.
A conventional fault inspection system of this type has been disclosed, in which the rotational speed of a rotary machine as a product to be inspected is changed in stages for frequency analysis. On the basis of the result of the frequency analysis, a frequency component corresponding to any abnormal noise of the rotary machine is detected to inspect an abnormality of the rotary machine. (See JP-A-59-97017, for example).
In the conventional inspection systems Configured as above, in which the rotational speed is changed and fixed in multiple stages, the inspection is both complicated and time consuming. As an improvement over these conventional systems, an idea may be suggested that the rotational speed of a rotary machine is changed continuously, a frequency component corresponding to an abnormal noise which may be generated from the rotary machine is extracted by way of a filter, and the level of the abnormal noise is inspected on the basis of such factors as a peak value, an impulse value and the average value of the extracted frequency component. In view of the fact that the sound pressure level of an abnormal noise is subject to change with the rotational speed, however, the detection sensitivity against the abnormal noise of the rotary machine is not satisfactory, resulting in a low detection accuracy.